Multistage liquid and gas separator

ABSTRACT

A liquid and gas separator having a primary stage including an agglomerator cartridge and a secondary stage providing the discharge path for the gas and liquid mixture passing from the primary state. The secondary stage includes a centrifugal separator with a flow reversing path and a combined minimum pressure discharge nozzle and collector chamber through which the separated gas and liquid are individually removed from the separator.

United States Patent Bloom Dec. 26, 1972 541 MULTISTAGE LIQUID AND- GAS612,207 10/1898 Kincaid 6181 ..55 45'/ x SEPARATOR 2,659,450 11/1953Baird ..55/396 2,848,060 3/1953 McBride 8181... ..55/325 lnvento" P"' 83,394,533 7/1968 Yi Sheng Li et 31.. ..55/337 3,538,684 11/1970 Esterho..55/457 X [73] Ass'gnee' 3235 Corporation y f 3,541,764 11/1970 Astromx..55 337 x 1,791,732 -2/1931 Manchester ..55/337 UX [22] Filed: Feb. 25,1970 FOREIGN PATENTS OR APPLlCATlONS [21] Appl.No.: 13,872

, 958,182 5/1964 Great Britain ..55/457 [52] U.S. Cl. 55/337, 55/396,55/457, Primary Examiner Tim R il 55/481 Assistant Examiner-VincentGifford [51] Int. Cl. Attorney Fishman and v [58] Field of Search..55/337, 456-457, 55/453, 447, 315, 318-319, 320-333, 392, 394, 396,447-450, 458-459, 497-498, 500, [57] ABSTRACT 434 235, 431, mg, 23, 461;210/304 A liquid and gas separator having a primary stage including anagglomerator cartridge and a secondary [56] References Cited stageproviding the discharge path for the gas and liquid mixture passing fromthe primary state. The UNITED STATES EN secondary stage includes acentrifugal separator with a 1,344,146 6 1920 Peck ..55/461x flowfFvel'siflg P and a combined minimum P 2 785 055 57 Redcay 55 x suredischarge nozzle and collector chamber through 2,828,831 4/1958 Borettiet a1..... 55/392X which the separated gas and liquid are individually3,347,026 10/1967 Zankey ..55l481 X removed from the separator.3,386,230 6/1968 Riesberg et al.. ..55/457 X 2,753,954 7/1956 Tinker.55/450 X 9 Claims, 2 Drawing Figures PATENTED 0m 1912 3.707.068

INVENTOR CARL BLOOM Allorneys MULTISTAGE LIQUID AND GAS SEPARATOR Arelated liquid and gas separator is shown in my copending US. Pat.application Ser. No. 14,306 filed Feb. 26, 1970 having the sameassignee, now US. Pat. No. 3,654,748.

BACKGROUND OF THE INVENTION 1. Field of the Invention The inventionrelates to the field of liquid and gas separators which employ bothagglomerating and centrifugal separating stages through which the liquidand gas mixture passes serially during the separating process.

2. Description of the Prior Art Liquid and gas separators which employ aplurality of stages for filtering or separating the liquid-and gasmixture are well known in the art. Such devices have a multitude ofapplications wherever either a purified gas mixture, or a purifiedliquid or both purified liquid and gas are desired. An example of thelatter situation is commonly found in rotary vane or screw-type gascompressors where lubricating oil is injected into the compressor tocool and lubricate the compressor as it is operating. The high pressureair leaving the compressor is laden with a great deal of the lubricatingoil. It is desirable to have the air purified for use with variouspneumatic devices, such as air hammers, and to have the oil returned toa reservoir for recirculation through the lubricating system of thecompressor.

Liquid and gas separators which are particularly adapted to air and oilmixtures often employ an agglomerator cartridge through whichthe oilladen air is passed. The cartridge causes the finely divided, atomizedparticles of oil to agglomerate in large droplets. The heavier dropletsreact more significantly to inertial forces than the atomized particlesand consequently larger quantities of oil can be more easily removedfrom an air flow by centrifugal separators. If the air stream has afairly high velocity, the stream may recapture atomized particles fromthe previously agglomerated oil. For these reasons efficient centrifugalseparators used in series with the agglomerator cartridges aredesirable.

SUMMARY THE INVENTION "The present invention relates to an improved,multistage liquid and gas separator. The multistage separator employs anagglomerator cartridge and centrifugal separators which receive the gasand liquid mixture after it has passed through the cartridge.

The agglomerator cartridge which forms the principal portion of theinitial or primary separating stage is mounted in a tank that receivesthe liquid and gas mix-.

to the outlet from the cartridge. Sharp bends are included in theconduit in order to throw the agglomerated droplets against the walls ofthe conduit from which it may drain by nally with helical swirl vaneswhich will throw entrained liquid against the side walls of the conduit.The annular passageway formed between the tapered center body and theinner surface of the conduit terminates in a collector chamber where thegas is decelerated and the liquid particles are carried by inertiaagainst the walls of the chamber. From the collector chamber the gasflow is turned back into the. hollow center body where it is againturned 180 into the entrance of a discharge tube. The tube may include aventuri portion for maintaining a desired minimum operating pressurewithin the tank. I

Liquid particles which are thrown against the walls of the conduit dueto the centrifugal forces and inertial forces drain into the lowerportion of the collector chamber by gravity. A scavenging duct leavingthe collector'chamber removes the collected liquid. The flow- BRIEFDESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a tankincluding a prima ry separating stage with an agglomerating cartridgeand the secondary centrifugal separating stage forming the dischargingpassageway for the mixture from the primary stage.

FIG. 2 is a sectional view of the primary separating stage along thelines 22 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference to FIG. 1 shows myimproved liquid and gas separator in a sectional view.

As indicated by the arrows the liquid and gas mixture enters the tank 10through a fitting 12 connected to one end wall of the tank and isdeflected downwardly by baffle 13. The fitting 12 may be connected tothe discharge manifold of a rotary vane compressor in which event thetank would be more commonly known as a demister tank for separating anair and oil mixture. Heavy particles of liquid entrained in the gasstream entering fitting 12 may immediately fall to the pool 14 of liquidin the bottom of the tank as the deflected gas stream decelerates. Ifdesired, the pool 14 may be drained through a convenient outlet 15 orsimply stored in the tank 10 for removal at periodic intervals.

Once in the tank, the liquid and gas mixture drifts toward the primaryseparator generally designated by numeral 16. This separator has acylindrical outer casing 18 including a longitudinal inlet slot 20 atits top side and a liquid drain line 22 at the bottom side. As seen moreclearly in FIG. 2, the mixture entering the casing 18 is forced tofollow the inner surface of the casing 18 by a baffle 24 which runscircumferentially from the inlet 20 along one side of the casing 18. The

baffle 24 is specially shaped to form a venturi section 26 and adiffuser section 28. The venturi section 26 causes the inflowing mixtureto be accelerated to a higher speed as it follows the cylindrical innerwall of casing 18. Some liquid particles entrained in the mixture arecentrifuged against the inner surface of casing 18 and eventually flowby gravity to the drain line 22. The diffuser section 28 decelerates themixture and therefore prevents the centrifuged liquid from beingrecaptured or aspirated in a high velocity gas stream. The mixture willcontinue to circulate around the inner surface of casing 18 and baffle24 and thusly will continue the centrifuging process. Eventually, themixture passes through an agglomerator cartridge 30 centrally positionedwithin the casing 18. The cartridge 30 consists of sheets of porous,filter material made from natural, plastic, glass or other fibers andcauses the finely divided particles to'coalesce in droplets. Thecartridge may be held in its cylindrical shape by means of a perforatedcage structure .32. At one end of the cartridge in FIG. I a seal 34prevents the mixture from bypassing the cartridge and flowing directlyto the centrally located outlet 36 in an end wall of casing 18. At theopposite end of the cartridge 8. closed cap'38 forming a part of thecage 32 seals the internal side of the cartridge from the external side.l

The casing 18 is mounted, to the end wall .40 of the tank by welds orany other convenient attachment. The end wall 40 may be a removable endwall secured to the remainder of the tank 10 by clamping bolts 42.Alternately, the wall 40 may be welded directly to the remainder of thetank to provide a less expensive construction. An access hole 44 and acover plate 46 held by a plurality of bolts 48 to the wall 40 arecoaxially aligned with the cylindrical casing 18. A cartridge spring 50is sandwiched between the cover plate 46 and the cap38 and urges thecartridge 30 with seals 34 into contact with the wall of casing 18surrounding the outlet 36. The removable cover plate 46 permits thecartridge 30 to be removed for inspection or replacement.

It will be understood that the centrifuging actionof the baffle 24removes a portion of the liquid entrained in the mixture ingested by theprimary separator 16. The centrifuged liquid flows by gravity to drainline 22. Drain line 22 extends from the separator 16 to, below thesurface of pool 14 since the slightly higher pressure outside of thecasing 18 would inhibit the draining of droplets by the gas flow as partof the first stage separating process. The recaptured portion of theliquid continues with the gas through the outlet 36. For this reason myinvention includes an improved secondary separator forming the dischargemechanism from the primary separator 16. v

The secondary separator receives the mixture with agglomerated dropletsin a conduit 60 connected to the casing 18 at the outlet 36. Gasentering the conduit 60 is initially turned through a sharp bendsubtending an angle preferably greater than 90. Some liquid carried bythe mixture at this point will be thrown against the outer wall of theconduit 60 by the centrifuging action. This liquid-will adhere to thewall and flow by gravity to lower portions of the conduit.

After passing through the sharp bend, the mixture enters a straightportion of theconduit 60 and meets a tapered hollow center body 62. Thecenter body 62 separates the flow as indicated by the arrows andaccelerates the flow through the annular passageway formed between thebody 62 and inner surface of conduit 60. The center body 62 issupportedwithin the conduit 60 by means of helical vanes 64which swirlthe accelerated flow. The combined acceleration and swirling by the body62 and vanes 64 centrifuges the entrained liquid against the walls ofconduit 60 where it can adhere and flow to a collecting chamber 66downstream of the annular passageway surrounding the center body 62. Asthe gas enters the collector chamber 66, it will be rapidly deceleratedfrom the high velocity in the annular passageway and further separationwill be caused by the inertial forces carrying the oil droplets againstthe end wall 40. In addition as indicated by the arrows, the gas isforced to reverse its flowdirection a first time to enter the hollowskirt section of body 62. A second flow reversal and consequently astill further separation due to inertial forces occurs within the hollowskirt section of body 62 where the gas enters a discharge nozzle 68. Thenozzle 68 leads directly to discharge aperture 70 in end wall 40. Thedischarge nozzle 68 has a-venturi form in which the throat isspecifically sized to provide chocked flow at a desired minimum upstreampressure. For various reasons it may be preferred to maintain a pressureno less than a given value at some point upstream of the nozzle 68 suchas the oil reservoir which feeds oil to the rotary compressor thatdischarges the mixture into tank 10. The discharge nozzle 68 willmaintain the desired pressure at choked flow regardless of the pressureat discharge 70. This nozzle and its function are described in greaterdetail in U.S. Pat. No. 3,318,514 issued May 9, 1967 to R. O. Garbus.

Through this series of centrifuging, decelerating and flow reversingactions large quantities of the gas-bome liquid will be thrown againstthe wall of my discharging mechanism. The liquid will eventually drainby gravity into the lowe portion of the collector chamber 66 from whichit will be removed through scavenging port 72 in end wall 40. As aresult, the gas leaving the tank 10 at discharge port 72 will besubstantially free of entrained liquid.

It will be understood that various modifications and substitutions canbe made in the particular embodiment shown. For example, it is notessential to the separating function that all components be mounted onthe coverplate 40. Such construction, however, permits the dischargingconnections and the access plate 46 to be located at one side of thetank which may be conveniently exposed externally for accessibility. Itmay be advantageous to include more than one bend in conduit 60 betweenthe outlet 36 and the center body 62. The discharge nozzle 68 need notbe a minimum pressure nozzle but may be a constant cross section tubesimply extending within the skirt section of body 62. Furthermore, theentrance of the nozzle 68 may be located closer to or immediatelyoutside of the opening of the skirt in center body 62 rather than deepwithin the body as shown.

Having thus described my invention, 1 claim:

1. A liquid and gas separating device comprising:

a. a housing defining a chamber for receiving a liquid and gas mixtureand having an end member including a gas discharge port;

b. a primary separator mounted to the end member within the chamber andhaving a mixture inlet, a liquid outlet, and a mixture outlet; and

c. a secondary separating and discharging means including:

l. a conduit connected with the mixture outlet of the primary separator;

2. a centrifugal separator interposed in the conduit and including ahollow, aerodynamically smooth center body having a closed end facingupstream toward the primary separator and an open end facing downstreamfrom the primary separator and a plurality of swirl vanes extending fromthe center body toward the inner surface of the conduit;

3. a gas discharge tube having a first end operatively connected withthe gas discharge port in the end member of the housing and a second endextending into the conduit at least to a position adjacent to andaxially aligned with the open end of the center body, the second endhaving crosssectional dimensions smaller than the correspondingdimensions of the open end of the center body; and

4. sealing means closing the conduit about the gas discharge tube.

2. The separating device of claim 1 wherein:

the second end of the gas discharge tube extends coaxially and partiallywithin the open end of the center body.

3. The separating device of claim 1 wherein:

the end member of the housing is a removable end member; and

the secondary separating and discharging means is supported by the endmember whereby the primary separator and the secondary separating anddischarging means is supported by the end member whereby the primaryseparator and the secondary separating and discharging means can beremoved with the end member.

4. The separating device of claim 1 wherein:

the end member of the housing additionally includes an access port and aremovable external cover plate closing the access port; and

the primary separator is mounted to the end member opposite the externalcover plate and includes an agglomerator cartridge removable through theaccess port.

5. The separating device of claim 1 wherein: I

the sealing means closing the conduit around the discharge tube alsoincludes a liquid drain port for removing liquid separated from the gasby the discharging mechanism.

6. The aratin device of claim 1 wherein: the (1186 rge tu e has aventurrsection, the throat of the venturi section having a crosssectional area providing choked flow at a preselected inlet pressure ofthe demister tank.

7. The separating device of claim 1 wherein:

the secondary separating means conduit includes at least one curvedportion subtending an angle greater than at a position upstream of saidcentrifugal separator.

8. The separating device of claim 1 wherein said primary separatormixture outlet faces into said chamber and away from said end member andsaid secondary separating means conduit contains a curved portion whichdefines an arc in excess of 90.

9. The separating device of claim 1 wherein said primary separatorcomprises:

1. A liquid and gas separating device comprising: a. a housing defininga chamber for receiving a liquid and gas mixture and having an endmember including a gas discharge port; b. a primary separator mounted tothe end member within the chamber and having a mixture inlet, a liquidoutlet, and a mixture outlet; and c. a secondary separating anddischarging means including:
 1. a conduit connected with the mixtureoutlet of the primary separator;
 2. a centrifugal separator interposedin the conduit and including a hollow, aerodynamically smooth centerbody having a closed end facing upstream toward the primary separatorand an open end facing downstream from the primary separator and aplurality of swirl vanes extending from the center body toward the innersurface of the conduit;
 3. a gas discharge tube having a first endoperatively connected with the gas discharge port in the end member ofthe housing and a seCond end extending into the conduit at least to aposition adjacent to and axially aligned with the open end of the centerbody, the second end having cross-sectional dimensions smaller than thecorresponding dimensions of the open end of the center body; and 4.sealing means closing the conduit about the gas discharge tube.
 2. acentrifugal separator interposed in the conduit and including a hollow,aerodynamically smooth center body having a closed end facing upstreamtoward the primary separator and an open end facing downstream from theprimary separator and a plurality of swirl vanes extending from thecenter body toward the inner surface of the conduit;
 2. The separatingdevice of claim 1 wherein: the second end of the gas discharge tubeextends coaxially and partially within the open end of the center body.3. The separating device of claim 1 wherein: the end member of thehousing is a removable end member; and the secondary separating anddischarging means is supported by the end member whereby the primaryseparator and the secondary separating and discharging means issupported by the end member whereby the primary separator and thesecondary separating and discharging means can be removed with the endmember.
 3. a gas discharge tube having a first end operatively connectedwith the gas discharge port in the end member of the housing and aseCond end extending into the conduit at least to a position adjacent toand axially aligned with the open end of the center body, the second endhaving cross-sectional dimensions smaller than the correspondingdimensions of the open end of the center body; and
 4. sealing meansclosing the conduit about the gas discharge tube.
 4. The separatingdevice of claim 1 wherein: the end member of the housing additionallyincludes an access port and a removable external cover plate closing theaccess port; and the primary separator is mounted to the end memberopposite the external cover plate and includes an agglomerator cartridgeremovable through the access port.
 5. The separating device of claim 1wherein: the sealing means closing the conduit around the discharge tubealso includes a liquid drain port for removing liquid separated from thegas by the discharging mechanism.
 6. The separating device of claim 1wherein: the discharge tube has a venturi section, the throat of theventuri section having a cross sectional area providing choked flow at apreselected inlet pressure of the demister tank.
 7. The separatingdevice of claim 1 wherein: the secondary separating means conduitincludes at least one curved portion subtending an angle greater than90* at a position up-stream of said centrifugal separator.
 8. Theseparating device of claim 1 wherein said primary separator mixtureoutlet faces into said chamber and away from said end member and saidsecondary separating means conduit contains a curved portion whichdefines an arc in excess of 90*.
 9. The separating device of claim 1wherein said primary separator comprises: convergent-divergent passagemeans for accelerating the mixture delivered to said mixture inlet; andagglomerator means connected between the divergent portion of saidpassage means and said mixture outlet.